A magnetic angle sensor may be used to detect a rotational position or movement of a shaft. Typically, a permanent magnet is attached to a rotatable shaft and a single magnetic field sensor is placed on the rotation axis and adjacent to the magnet.
A disadvantage of known solutions is that they are very sensitive to magnetic disturbances. For example, if the magnet generates a field of, e.g., 45 mT at the sensor elements, a magnetic disturbance amounting to, e.g., 3 mT (in a worst case direction perpendicular to the axis and orthogonal to the field of the magnet) leads to an error amounting to 3.8° (arctan(3/45)=3.8°), which is generally not acceptable.
Magnetic disturbance fields are prevalent in vehicles such that magnetic angle-measurements often have to endure harsh environments. This is especially problematic in new hybrid and electric vehicles, where many wires with high currents are located near the sensor system. Thus, external magnetic disturbance fields may be generated by current-rails in a vehicle that influence the accuracy of the magnetic angle measurements.